(1) Conventionally, in a punch processing machine, there is provided a tool management device as disclosed, for example, in Japanese Patent Application Laid-Open No. 61-99529 (FIG. 1 in the same Gazette).
In this case, the punch processing machine is, for example, a turret punch press (FIG. 2 in the same Gazette), and in a condition that a tool (punch and die) to be used is selected, immediately beneath a ram (striking element), the ram press-strikes the selected tool (punch), thereby the turret press performs punch processing on works.
Each time when aforementioned ram press-strikes a tool, a tool management device of such a turret punch press counts number of uses of the tool and is designed to issue an alarm, when the counted number of use reaches a pre-set durable number of uses.
However, the aforementioned conventional tool management device is dedicated to a punch processing machine, and thus it can not be applied to a press brake as it is.
In other words, in the punch processing machine, as described previously, only tool to be used just now is selected and arranged immediately beneath the ram.
Contrary to this, in the press brake, as illustrated in FIG. 3 of the present application for example, a number of work stations ST1, ST2 . . . are formed in a ram (e.g., an upper table 12), and there are metal molds to be used and the ones not to be used depending on bending sequences, among divided tools 1, 2 . . . , that constitute respective work stations ST1, ST2, ST3 . . . .
Accordingly, the number of operations of ran and the number of uses of metal molds are in one-to-one correspondence, in a punch processing machine, whereas they are not in one-to-one correspondence in a press brake.
Thereby, in the punch processing machine, when the ram operates one time to press-strike a tool, the tool is certainly used one time, whereas in the press brake, if the ram is operated one time, the tool mounted on the ram is not necessarily used one time.
For example, in the FIG. 3, in the work station ST2, when a ram 12 operates one time, since a bend line m3 portion of a bending length L3 positioned at a predetermined bending position X3 is machined, in a bending sequence (3), tools A2, C1 that constitute a tool layout c are used each one time.
However, even at the same work station ST2, since a bending line m4 portion of a bending length L4 positioned at a predetermined bending position X4 is machined, in a bending sequence (4), all of tools 5, A2, C1, and 6 constituting a tool layout d, that is, all tools 5, A2, C1, and 6 constituting the tools A2, C1 of the tool layout c used in the bending sequence (3) are used each one time.
For this reason, if a method for managing tools is adopted where each time a ram 12 operates one time, tool is supposed to have been used one time, using the conventional tool management device, there is too big difference from actual number of use, and it becomes quite uncertain which tools were used how many times. As a result, in a press brake, management of metal molds is not fully performed, and it is difficult to grasp wear condition of each tool. When bend processing is performed in such a condition, angles α, β, γ along the bend line m portion of a machined work W become unequal to one another, as illustrated in FIG. 8, and integrated uniform accuracy will be deteriorated.
Also, practically, although the number of use of a certain tool does not reach durable number of uses, the tool is sometimes polished by mistake. As a result, waste of working man-hours is produced resulting from low efficiency of tool management and performing extra polishing operation.
(2) Further, as described in the above paragraph (1), in the press brake, unlike a punch processing machine, a tool layout in a work station on the ram is comprised of a plurality of divided tools, and the number of operations of ram and the number of uses of tools do no correspond to one-to-one correspondence. Accordingly, a tool management device as disclosed in the Japanese Patent Application Laid-Open No. 61-99529 can not be applied to the press brake.
Hence, the applicant of the present application filed a patent on Jun. 15, 2005, with respect to a tool management device through a scheme for counting number of uses of each tool that actually bends works (Japanese Patent Application No. 2005-175300).
Then, be it a tool management device as disclosed in the Japanese Patent Application Laid-Open No. 61-99529 or a tool management device as disclosed by the applicant of the present application, in a conventional press brake, for a tool in which number of use does not reach durable number of use, a tool layout is prepared by the next operation.
For example, in the case where the tool layout is prepared in a work station with a length of 470 mm, first, for example, a stocker h1 for long tools with a cross-sectional shape of A within a tool (punch) storing section 2 (FIG. 10) is shifted to the side of upper table 12 (FIG. 26(A)), and subsequently only tools with ID numbers 1 to 4 out of seven tools (identification (ID) numbers 1 to 7) stored within the stocker h1 for long tools are inserted into the upper table 12 side (FIG. 26(A)) by a tool (punch) exchanging device 2A (FIG. 9).
In this condition, by shifting the tools with ID numbers 2 to 4 to left side among the tools that have been inserted into the upper table 12 side (FIG. 26 (B)), a clearance is formed between the tools with ID number 1 and 2.
After that, this time, a stocker t (FIG. 10) for short tools with the same cross-sectional shape of A is shifted to the side of upper table 12 (FIG. 26(C)) in a similar way, and subsequently the tools with ID numbers 5 (20 mm in length) and 13 (50 mm in length) are inserted between the clearance of upper table 12 side.
Finally (FIG. 26 (D)), a tool layout with length of 470 mm can be prepared if clearance is eliminated by putting the tools of upper table 12 side together.
However, a conventional system for selecting tools, as described previously, is a system where, in both stocker h1 for long tools and stocker t for short tools, metal molds are selected in sequence in the increasing order of ID number, and this also applies to a tool storing section 3 (FIG. 11) in which dies are stored.
For this reason, as illustrated in FIG. 25, conventionally, a metal mold with a smaller ID number has a significantly greater number of use compared to that of a larger ID number, thus the proportion that punch's tip and die shoulder are worn becomes larger by the increment of use.
As a result, as illustrated in FIG. 27, angles α, β, γ along the bend line m portion of the machined work W become unequal to one another and bending angles become loose, and thus integrated uniform accuracy becomes deteriorated.
In other words, conventionally, because tools with smaller ID numbers tended to be used frequently (FIG. 25), the wear condition was also nonuniformly heavily produced in the tools with smaller ID numbers, and consequently integrated uniform accuracy was deteriorated.
A first object of the present invention is to provide a bending-apparatus and a method for managing tools that perform relevant tool management by measuring number of uses of individual tools that actually bent-works, as well as performing bend processing with a good integrated uniform accuracy, in order to solve the above-mentioned problem in (1).
A second object of the present invention is to provide a bending apparatus and a method for arranging tools which perform bend processing with a good integrated uniform accuracy by achieving uniformity of wear condition of metal molds and a method for selecting a tool stocker, in order to solve the above-mentioned problem in (2).